_
40
EFFECT on
TRAWLING ON ANNELIDS.
injuredwonld
On the other hand, many ne examples
—
frequent the rocky borders where
trawl can touch them
The delicate heart—urchins are, for the most part, ruined in
trawl, yet the habitat “of many is deeply buried in the sand
beyond the reach of ‘sole ’—rope or iron trawl-heads.
Then,—
again, how many liners, how many musseI—, dam-, and oystcr—
farmers, would gladly subsidise the trawler to
the
:
swarms
of common cross—shes, whose multitudes form, for…
acres, a carpet on the bed of the ocean}
_
‘
Not a few annelids, such as sea—mice, nèreids,
‘
serpu1ids, and nemerteahs are entangled in the ground—rope
and the net of the trawl, or in old shells and other débris from—
’
the bottom; but the injury to this group, as formerly mentioned,—
is- not great, for many reach the sea alive amongst the
'
and regene1‘ate lost parts or discharge their ova into the surrounding water, or the larvæ swim from under the sCales 01“
frOm-the sacs.
It is an interesting fact in this connection that
_
certain annehds at the breeding season
_
undergo a change f—
_
form, leave the rocks, cavities under stones, or Other placesof:
shelter, and Swim free1y in the water (that is, become pelagm),‘
discharging— their reproductive elements when thus en voyage
_
It is during these pelagio periods that the huge Alitta wens
{a worm reaching occasionally about 8 feet, and a valuablebalt
‘
for shes)is thrown ”by storms in great numbers on the sands,
_
”…eyen before the function for which nature ordained the pelag10
is performed. In the same way, Mr Thomas
and
_Duthie, frecently found the inshoire water at Castlebay,
with the sexual forms Of a Neré7]s… An
examination _,of the stomachsof food-shes shows that sucha
Pl°Vlswnasthe , füregoing is…du1_ytàkeu advantage of bythem
18W6“ Since
anne-Eds are… destied t0 Peushafter
SPeŒaYüeated°fmanyyears »@g0ä and «in «the recent Repœts
oftherheyBoadfrthe11mest1gaüoæh… been nadeby